Modelling low pressure LLE and VLE of methanol/alkane mixtures with a modified Peng-Robinson EoS and the Huron-Vidal mixing rules

Juan P. Hernández, Luis A. Forero, Jorge A. Velásquez

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    Abstract

    In this work, it is assessed the capabilities and limitations of a simple cubic EoS/GE thermodynamic model to describe the phase equilibria of methanol/alkane mixtures using generalized binary interaction parameters. In first place, the critical properties of the n-alkanes were selected to generalize the parameters of the model by fitting the liquid-liquid equilibria (LLE) of binary mixtures formed by methanol with pentane, heptane and decane respectively. Adequate description of the LLE coexistence curve can be obtained at atmospheric pressure for mixtures with n-alkanes in the 4-10 carbon number range. Also, it is possible to represent the mathematical behavior of the UCST of the methanol alkane series according to literature. Finally, some predictions were made for vapor liquid equilibria (VLE) and vapor-liquid-liquid equilibria (VLLE) conditions at low and high pressure. In general, predictions are unsatisfactory. In some cases, at low pressures, qualitative predictions for the azeotropic behavior can be obtained. In second place, a second set of generalized parameters were obtained by fitting the VLE of binary mixtures formed by methanol with propane, pentane and hexane. Using this new set, the model is capable to reproduce in qualitative way the high-pressure vapor-liquid equilibria of methanol/alkane mixtures between propane and decane. However, for LLE equilibria the results are inadequate from qualitative and quantitative points of view. Based on the results found in this work, it can be established that the selected model is not capable to describe simultaneously the VLE and LLE of methanol/alkane type mixtures reasonably with a single set of binary interaction parameters.

    Original languageEnglish
    Article number113123
    JournalFluid Phase Equilibria
    Volume546
    DOIs
    StatePublished - 15 Oct 2021

    Bibliographical note

    Funding Information:
    The authors thank the support of the Ministry of Science, Technology and Innovation of Colombia, for the financial support through the Program of Postdoctoral projects 2018. The authors thank the support of the Faculty of Chemical Engineering of the Universidad Pontificia Bolivariana.

    Publisher Copyright:
    © 2021 Elsevier B.V.

    Keywords

    • Alkanes
    • Huron-Vidal mixing rules
    • Liquid-Liquid equilibria
    • Methanol
    • Peng-Robinson EoS

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